We propose to use our newly developed specific immunoassay for urinary kallikrein, together with standard bioassays and esterase assays, to evaluate the role of the renal kallikrein-kinin system in man. Physiological studies will include the effects of changing sodium, potassium and water metabolism. Clinical studies of kallikrein in kidney disease, hepatorenal syndrome, Bartter's syndrome and other relevant human diseases, will be performed.